The invention concerns a suction jet pump for delivering fuel, for example for a vehicle.
Many motor vehicles, such as for example cars, buses and trucks, have a fuel supply module which comprises a tank in which the fuel for the vehicle is stored. In the tank is a reservoir which is used to provide fuel even if the tank is almost empty or if the fuel is no longer evenly distributed in the tank due to centrifugal forces occurring during travel. A fuel pump can be located in the tank and for example is driven by an electric motor and delivers the fuel in the direction of the vehicle engine and in the direction of a jet pump. The jet pump serves to deliver fuel from the tank into the reservoir so that the reservoir always contains sufficient fuel. The fuel supply module thus has a reservoir actively filled by the jet pump.
The jet pump is a pump in which the pump action is generated by a jet of fuel which is produced by a small nozzle opening on the jet pump and which draws up further fuel from the tank, accelerates it and delivers it into the reservoir. The nozzle opening can have a diameter of around 0.6 mm and is usually protected by a pre-filter so that no particles in the fuel can clog the nozzle opening. For example the pre-filter can be provided as an additional part in the supply line to the jet pump.
In order to reduce the consumption of fuel by the jet pump as a propellant, which can reduce the energy consumption of the jet pump, the nozzle opening can be reduced. This can for example be achieved by a smaller diameter for the nozzle opening. Normally the jet pump is made of plastic, for example by means of injection molding, in particular as part of the reservoir wall. However on reduction of the nozzle opening, problems can arise since difficulties or errors can occur on forming a nozzle with a small nozzle opening in a large plastic mold. For example in this case the nozzle opening can break on removal of the formed jet pump from the mold.
The nozzle opening currently in general use, with a diameter around 0.6 mm, can be produced with a special part of the mold, which however creates an additional hole in the pump body of the jet pump. The additional hole must then be plugged with a further part, such as ball or similar.